Enabled flag

[zaalbarxx]

Fixes #274
Added for both component and directive. I could propably be possible to also add it to composable, but it would require some changes to types like

type UseTippyOptions = UseTippyOptions & { enabled?: MaybeRefOrGetter }

...
`watch(() => opts.enabled, (newValue) => {
// same logic as in PR
});

Let me know if that makes sense, personally I stumbled upon the issue with directive not being "controllable" today, so I've made a quick fix with this code and it works fine, but maybe it could make the way to the package itself.
Cheers

export const disableableTippy: Directive = {
    ...directive,
    mounted(el, binding, vnode) {
        (directive as any).mounted(el, binding, vnode);
        if (!el.$tippy) {
            return;
        }

        const isTippyEnabled = el.$tippy?.state.value.isEnabled;

        if (binding.value.enabled && !isTippyEnabled) {
            el.$tippy.enable();
        } else if (!binding.value.enabled && isTippyEnabled) {
            el.$tippy.disable();
        }
    },
    updated(el, binding) {
        (directive as any).updated(el, binding);

        if (!el.$tippy) {
            return;
        }

        const isTippyEnabled = el.$tippy?.state.value.isEnabled;

        if (binding.value.enabled && !isTippyEnabled) {
            el.$tippy.enable();
        } else if (!binding.value.enabled && isTippyEnabled) {
            el.$tippy.disable();
        }
    },
};